Structural analysis of radiation-grafted polymer electrolyte membranes by dissipative particle dynamics simulation

Abstract

We investigated for the first time the mesoscopic structure of crosslinked-polytetrafluoroethylene (cPTFE) based radiation-grafted polymer electrolyte membranes (PEMs) by using dissipative particle dynamics (DPD) simulation. Based on the molecular structures, the fully-hydrated PEM systems were constructed with coarse-grained particles representing several atom groups. In the equilibrium state, water appeared to percolate into poly (styrene sulfonic acid) (PSSA) graft chains to give a mixed phase, separated from the hydrophobic PTFE chains. This phase-separation picture is quite different from that of Nafion, in which only water particles were gathered excluding any polymer parts (formation of a so-called water cluster). In order to obtain a deep insight into the phase-separation structure, the radial distribution function between water particles was calculated. As a result, there were found to be small water clusters with a diameter of only 1.8 nm in the water/grafts mixture regions. © 2010, The Society of Polymer Science,.